الفهرس 
ANATOMY OF THE URINARY SYSTEMOnly 14 pages are availabe for public view
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Abstract
Urothelial tumours arise in the epithelial lining of the urinary tract and include transitional cell carcinoma (TCC), squamous cell carcinoma, and adenocarcinoma.The vast majority are transitional cell carcinomas (90%).
TCC is 30-50 times more common in the bladder than ureters and renal pelvis.Urothelial carcinoma has a propensity to be multicentric with synchronous and metachronous bladder and upper tract tumors. Hematuria is present in 72% of patients.
Patients with suspected urinary tract disease are often referred for multiple studies such as excretory urography (EU), ultrasound (US), CT or MRI. Multi-examination work-up require much patient effort and are expensive. A single imaging test that comprehensively evaluates the urinary tract has advantages in terms of both convenience and cost.
CT is already widely acknowledged superior to EU and US in its ability to detect and characterize renal masses. The last remaining potential limitation of CT for examination of the urinary tract is its perceived limited accuracy in assessment of the mucosal surfaces of the renal collecting systems and ureters.
Finally, with the advent of multidetector CT, CT became capable of producing a large number of thin section images in a short period of time. As a result, the spatial, temporal, and contrast resolution became sufficient to image the urothelium. CT urography can demonstrate not only urinary tract lumen but also the wall of the urinary tract and its surrounding structures.
Increased volume coverage is combined with thinner slice thickness to obtain better quality volume data sets for workstation analysis, either in 2-D axial, multiplanar reformation (MPR), or three-dimensional (3-D) imaging.
One of the main advantages of Multi detector CT urography (MDCTU) is its ability to display the entire urinary tract, including renal parenchyma, pelvicalyceal systems, ureters, and the bladder using a single non-invasive imaging test, in one breath-hold. The alternative imaging studies alone do not offer equivalent coverage. So that , MDCTU became the “core” imaging study for investigation of hematuria as it has the potential to stand alone as a comprehensive “one-step” test for imaging the upper and lower urinary tract.
Multiphasic CT urography offers superior detection of urothelial tumors over EU and US and allows accurate staging of detected lesions at the same examination.
Magnetic resonance urography (MRU) has advantages over MDCTU including the ability to detect early stages of the urothelial tumors & imaging the pelvicalyceal systems without intravenous iodinated contrast agents using heavily T2 weighted ultrafast sequences. Another advantage of MRU is that the significant radiation dose associated with the other modalities is avoided.
The early detection of TCC is very important for the planning of limited surgical treatment. MDCTU is capable of identifying lesions at an early stage, thereby allowing nephron-sparing surgery.
In conclusion, MDCT urography is a versatile imaging test which can detect urothelial malignancies, whether they present as large masses, small masses, or urothelial wall thickening , more over it can even identify some renal collecting system or ureteral segments in which carcinoma in situ is present. MDCT urography can identify papillary and flat, high-grade and low-grade malignancies, and also has a well-established role in staging these tumors.